Keyed oscillator



Dec. 14, 1948. R.' P. OWEN I KEYED OSCILLATOR Filed sept. 1e, 1944 WINVENTOR.

Patented Dec. 14, 1948 B. DuMont Laboratories, Inc.,Passai'c,

a'corporationfDelawarej 1 Apllicationseptember 16,1?944, serial-NassijszThis invention relates toa vacuum tube oscillator by which trains orbursts' of oscillations, either sinusoidal or oi othery shapes, can besuddenly initiated and' caused to continue for predetermined intervalsof time,Y and their be'suddenly,

stopped. With `this invention.;l the initationiwof the oscillations andthe stopping of the'sameis under the control of another vacuum tube andmay be done by means of a pulse of electrical energy that may be termedkeying pulse.

The invention may be understood from the description in connection withthe accompanying drawing, which is a diagram of connections showing anillustrative embodiment of the invention.

In the drawing, reference character I indicates the vacuum tube of atransitron oscillator which is provided with a plate 2, cathode 3, andthree grids 4, and 6, the grid B being grounded.

A resistor I is provided between a source of positive potential B andthe plate 2. A resistor 8 is provided between the plate 2 and groundwith -a condenser 9 in parallel with the resistor 8. A

variable resistor IIl is provided between the cathode 3 and ground witha condenser II in parallel with it. A condenser I2 is connected betweenthe grids 4 and 5 and a resistor I3 is located between grid 4 andground.

`grid 5 constitutes th'e tank circuit of this grid and controls thefrequency of oscillations of the tube I in the known way.

The output lead from the oscillator I is indicated' by I6. A lead I1 isconnected from the lead I6 to the plate I8 of the triode I9 which is thekeying tube for the device. It has its cathode 28 biased by resistor 2lwith which the condenser 22 is in parallel.

The keying pulse 24 is coupled by condenser 25 tothe control grid 26 ofthe tube I9. This grid 2B is connected to ground through resistor 21.

The operation is as follows:

The pentode I is connected yas shown as a transitron oscillator. It hasbeen found, for example, that the device Aoperates very satisfactorilywhen the resistor ID is adjusted-to be about 300 ohms and the potentialB-iis about 85 volts. A wide range of frequencies of oscillation of theoscillator I can be obtained by changing the condenser I4 or inductanceI5,r It has been found misst-36 'cause of the low alternating currentplate to cathode resistance of tube I9, which isfeflectively acrossfthetank coil I5. The resistor 2l prevents y:excessive current. through tubeI9. fr f, However, when anegative pulse as indicated at 241s. appliedvto the control grid 26 )of tube I8,

@this tube: .ceases to conduct, thus causingr itsr plate towcathod'eimpedance. to become very/ high, whereupon the oscillator I begins tooscillate instantly at the frequency determined by the grid or bursts ofoscillation, whether of sinusoidal or l other forms, can be suddenlyinitiated, prolonged for different intervals of time, and immediatelyextinguished merely by applying the appropriate signals to the grid oftube I9.

What is claimedy is:

1. A device for producing bursts of electrical oscillations, whichcomprises a pentode that has its control grid grounded and its cathodeconnected to ground through a resistor, a condenser and inductance inparallel connected between a source of positive potential and the screengrid of said pentode, a resistor between the suppressor grid of saidpentode and ground and a condenser between the screen grid andsuppressor grid of said pentode to cause said pentode to oscillate whenpositive potential is applied to its plate, a triode adapted to beblocked when a pulse of negative potential is applied to its controlgrid, the plate of said triode being connected directly to said screengrid and its cathode connected to ground through a resistor.

2. A d evice for producing bursts of electrical oscillations, whichcomprises a pentode that has its control grid grounded and its cathodeconnected to ground through a resistor, a condenser and inductance inparallel connected between a source of positive potential and the screengrid of said pentode, a resistor between the suppressor grid of saidpentode and ground and a condenser between the screen grid andsuppressor grid of said pentode to cause said pentode to oscillate ywhenpositive potential is applied to its plate, a

triode adapted to be blocked when a pulse of negative potential isapplied to its control grid, the plate of said triode being connecteddirectly to said screen grid, and separate resistors conbetween thescreen grid and suppressor grid of said pentode to cause said pentode tooscillate when positive potential is applied to its plate, a triodeadapted to be blocked' when a :pulse of negative potential is applied toits control grid, the plate of said triode being connected directly tosaid screen grid, and separate resistors connecting the cathodes of saidpentode and triode respectively to ground and a condenser in parallelwith each resistor.

4. A device for producing bursts of electrical oscillations, whichcomprises aperitode that has its control grid grounded and its cathodeconnected to ground through a resistor, a condenser and inductance inparallel connected between a source of positive potential and the screengrid of said pentode, a resistor between the suppressor grid of saidpentode and ground and a condenser between the screen grid andsuppressor grid of said pentode to cause said pentode to oscillate whenpositive potential is applied to its plate, a triode adapted to beblocked when a pulse of negative potential is applied to its controlgrid, the plate of said triode being connected directly to said screengrid, a variable resistor between the cathode of said pento'deandg'groudand a re..

sistor between the cathode of -said triode and ground.

` ROBERT P. OWEN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,839,650 Cook Jan. 5, 19322,088,229 Braden July 27, 1937 2,213,398 Kircher Sept. 3, 1940 2,273,193Helsing Feb. 17,1942

OTHERl REFERENCES The Transitron Oscillator, by Cledo Brunetti,Proceedings of the I. R. E., pages 88-93. Copy in Library.

